Related Field
The present invention relates to a touch sensor integrated display device and a method for driving the same.
Discussion of the Related Art
Touch sensors are being proposed which enable users to directly touch or get close to the screen and enter data with their finger or a pen while watching displays of a variety of home electronics or data communication devices. The touch sensors are used for various display devices because they are simple to use, have low possibility of malfunction, allow for user input without using an additional input device, and enable the users to operate them quickly and easily through content displayed on the screen.
The touch sensors may be implemented by well-known technologies such as capacitive sensing, infrared (IR) sensing, etc.
Capacitive sensing may be classified into add-on type, on-cell type, and in-cell type.
In the add-on type, as shown in FIG. 1, a display device 1 and 2 and a touch film 3 with touch sensors are separately manufactured, and the touch film 3 is attached to the surface of the display device. In FIG. 1, reference numeral 1 denotes a display panel, reference numeral 2 denotes an encapsulation substrate, and reference numeral 4 denotes a touch IC. The add-on type has the problem of low visibility caused by its large thickness and the low brightness of the display device 1 and 2 because a finished touch film 3 is mounted over the display device 1 and 2.
In the on-cell type, touch sensors are directly formed on the surface of an upper glass substrate of a display device. In case of the on-cell type, touch sensors are formed on the upper surface of a display device, with a reduction in thickness compared with the add-on type, but still a driving electrode layer and sensing electrode layer constituting the touch sensors and an insulating film for insulating these layers increase the entire thickness and the number of process steps, leading to an increase in the manufacturing cost.
In the in-cell type, touch sensors are formed inside a display device, which is attracting a lot of attention in that the touch sensors can be made thin. Known examples of the in-cell type touch sensors include mutual capacitance touch sensors and self-capacitance touch sensors. In mutual capacitance sensing, driving electrode lines and sensing electrode lines cross each other within a display panel to form touch sensors, a touch driving signal is applied to the driving electrode lines, and then touch input is sensed by detecting a change in mutual capacitance at the touch sensors through the sensing electrode lines. In self-capacitance sensing, touch electrodes and sensor lines are formed on a display panel, a touch driving signal is applied to the touch electrode through the sensor lines, and touch input is sensed by detecting a change in self-capacitance at the touch electrodes.
The in-cell type too requires signal lines (e.g., driving electrode lines, sensing electrode lines, and sensor lines) associated with touch to be added on the display panel. Moreover, the in-cell type requires an electrode patterning process because an internal electrode used for display is used as an electrode of the touch sensors to achieve a thin profile and has large parasitic capacitance due to the coupling between touch sensors and pixels. This leads to a reduction in touch sensitivity and touch recognition accuracy.
In IR (infrared) sensing, as shown in FIG. 2, a display device 1 and 2 and a touch bezel 5 with touch sensors are separately manufactured, and the display device 1 and 2 and the touch bezel 5 are joined together. In FIG. 2, reference numeral 1 denotes a display panel, reference numeral 2 denotes an encapsulation substrate, and reference numeral 4 denotes a touch IC. IR (infrared) sensing does not support multi-touch due to the low response rate and the low touch resolution.
As seen from above, the conventional touch sensor technology requires complicated elements for touch sensing to be added on a display device, which complicates the manufacturing process, increases the manufacturing cost, and lowers touch sensing capabilities.